This invention relates to proteinaceous foods and more particularly to animal foods of the shelf-stable, intermediate moisture variety.
Until the past decade animal foods were sold either in dry or canned form. The dry variety of animal foods usually contains less than 10% moisture and hence does not require sterilization procedures or refrigeration in order to render them resistant to microbial decomposition. The dry animal foods, however, are generally characterized by their low degree of palatability, it being found that as a general rule palatability is enhanced at higher moisture contents.
Canned animal foods enjoy a significant degree of palatability owing primarily to their high moisture contents, typically in the area of 75%. However, this high moisture content necessitates the sterilization of such products, generally by retorting, and refrigeration once the can is opened. Thus, canned foods involve significant processing costs and a lack of consumer convenience.
A significant contribution in the animal food field was made by Burgess, et al in U.S. Pat. No. 3,202,514. Therein is described a pasteurized intermediate-moisture animal food based principally upon proteinaceous meaty materials which product is shelf-stable and resistant to microbial decomposition without the need for sterilization, refrigeration or aseptic packaging. The meaty animal food is stabilized by "water soluble solutes", principally sugar. The function of these solutes is to bind up available water in which microorganisms grow.
While the product of Burgess, et al represented a significant contribution to the state of the art, the need for improvement in this area has been and continues to be recognized. More specifically, prior art workers have attempted to improve the palatability of such products such that they achieve parity in this area with the more palatable canned animal foods. Palatability improvement may take a variety of forms, such as the overt addition of enhancers, the elimination of negative taste factors, the utilization of greater amounts of meaty materials, and increasing the moisture content.
Among the known negative factors in intermediate moisture animal foods are certain of the stabilizers, especially at relatively high levels. Thus, elimination or reduction in the level of these stabilizers would provide a boost in palatability. Moreover, reduction of the level of stabilizers required would also reduce costs, permitting a net savings or the use of more costly, flavorful ingredients in a product to be sold at the same price. Thus, by reducing the negative factors of the stabilizers, more of the positive factors of the animal food are allowed to exert their effect.
Among the stabilizers suggested by Burgess et al. are antimycotics such as sorbate salts and sorbic acid. Preferred sorbate salts are potassium, sodium and calcium sorbate. For all of these sorbates, it is known that their activity as antimicrobials decreases with increasing pH. Thus, where pH is maintained at substantially neutral values to assure palatability of a food for dogs, the amount of sorbate must be increased to assure effective protection. And, because the sobates are perceived as negative factors, the palatability at the near neutral pH is not as good as it would otherwise be because of these increased levels of sorbates. Other stabilizers which are known are edible aliphatic acids and their edible soluble salts, such as the acid and sodium and potassium salts of caproic, caprylic and propionic acids.
Thus, there is indeed a problem in properly stabilizing mold and bacteria susceptible foods, especially pasteurized intermediate moisture animal foods of the kind discussed by Burgess et al. containing sorbate and other aliphatic acid stabilizers.
It is therefore an object of the present invention to decrease the level of caproic, caprylic, propionic or sorbic acids or their salts needed to stabilize intermediate moisture foods against microbial growth.
It is a more specific object of the present invention to decrease the level of caproic, caprylic, propionic or sorbic acids or their salts needed to stabilize proteinaceous intermediate moisture foods, especially pasteurized, meat-containing animal foods against microbial growth.
This and other objects are accomplished by the present invention which provides an improved process for preparing a food containing mold and bacteria susceptible ingredients wherein caproic, caprylic, propionic and/or sorbic acid or a non-toxic salt thereof is employed as an antimicrobial wherein the improvement comprises:
packaging the food in a substantially gas impervious packaging material, and filling the free space in the package with carbon dioxide.